clc;
clear all;
close all;

fo = 4;   %frequency of the sine wave
Fs = 100; %sampling rate
Ts = 1/Fs; %sampling time interval
t = 0:Ts:1-Ts; %sampling period
n = length(t); %number of samples
y = 2*sin(2*pi*fo*t); %the sine curve
	
%plot the cosine curve in the time domain
sinePlot = figure;
plot(t,y)
xlabel('time (seconds)')
ylabel('y(t)')
title('Sample Sine Wave')
grid

% %plot the frequency spectrum using the MATLAB fft command
% matlabFFT = figure;  %create a new figure
% YfreqDomain = fft(y); %take the fft of our sin wave, y(t)
% 
% stem(abs(YfreqDomain));  %use abs command to get the magnitude
% %similary, we would use angle command to get the phase plot!
% %we'll discuss phase in another post though!
% 
% xlabel('Sample Number')
% ylabel('Amplitude')
% title('Using the Matlab fft command')
% grid
% axis([0,100,0,120])
% 
% [YfreqDomain,frequencyRange] = centeredFFT(y,Fs);
% centeredFFT = figure;
% 
% %remember to take the abs of YfreqDomain to get the magnitude!
% stem(frequencyRange,abs(YfreqDomain));
% xlabel('Freq (Hz)')
% ylabel('Amplitude')
% title('Using the centeredFFT function')
% grid
% axis([-6,6,0,1.5])

[YfreqDomain,frequencyRange] = positiveFFT(y,Fs);
positiveFFT = figure;
stem(frequencyRange,abs(YfreqDomain));
set(positiveFFT,'Position',[500,500,500,300])
xlabel('Freq (Hz)')
ylabel('Amplitude')
title('Using the positiveFFT function')
grid
axis([0,20,0,1.5])
